The present disclosure relates to cover systems for open-topped containers, such as dump bodies, refuse haulers, grain trailers and the like. These cover systems utilize flexible covers, such as tarpaulins, that are pulled across the open top of the container body. The flexible cover is wound onto a roller as the cover is moved to its open or stowed position and unwound from the roller as the cover is moved to a closed position covering the container body. An arm assembly supports the opposite ends of the flexible to control the movement of the cover to and from its end positions.
The conventional cover systems utilize torsion springs to propel the arms in one direction or another, typically from the open position to the closed, covering position. A motor winds the cover on the roller against the force of the torsion spring to pre-load the spring. When it is desired to deploy the cover, the motor is reversed and the torsion spring unwinds to gradually pull the cover to the covering position.
Torsion springs for cover systems can be underbody springs that are exposed to the harsh environment underneath a moving vehicle. Flat or spiral torsion springs are also used in cover systems, with the benefit of being contained within a housing at the side of the container body. However, each individual spiral spring does not provide enough torque to consistently move a typical cover system. Thus, multiple spiral springs are provided in a typical system, which increases the width of the spring pack and thus the width of the cover system. Various governmental regulations limit the width of a vehicle and thus the width that a cover system may extend beyond the sides of the vehicle. These width regulations limit the number of spiral springs that can be incorporated into a spring pack, and thus inherently limit the torque characteristics of the arm assembly.
Consequently, there is a need for a cover system that is capable of generating the torque profile needed to move a container cover system, while still maintaining a package dimension that meets all government width regulations.